抄録
In order to correlate the temperature dependence of critical COD, δc, with Charpy-V transition temperature, FATT, the statistical analysis was attempted on the available data of notch toughness.
About 1300 data on the notch toughness in the base metal and welded joint of mild steel and high strength steel were compiled from published and unpublished literatures.
Firstly, the statistical hypothesis that there exists the linear relationship between logarithm of δc, and reciprocal of absolute temperature was tested. As a result, the hypothesis was found to be significant. The coefficient of the linearity decreases with increasing strength and doesnot depend on FAIT.
Secondly, the correlationship between temperature at δc=0.16 mm and FATT was examined.
Finally, taking into account the uncertainties included in the estimation of δc. from FATT, the following equation was established with the aid of maximum likelihood method:
Inδc=In0.16-4328/√σY0(1/TK-1/TK0.16)+|0.86+14.0(1/TK-1/TK0.16)|z
whereTK=Tsv-6√B+303(K), TK0.16=γTS+σY0+153(K),
f(z)=1/√2πexp(-z2/2)(standard normal probability density function),
vTs: FATT (°C), Tsv: service temperature (°C),
σY0: yield stress at room temperature (kg/mm2), B: thickness of COD test specimen (mm).
